IT IS WELL substantiated that the mortality rate of primary cancer of the lung has reached major proportions.1This disease, which in the not too distant past was regarded as unusual in occurrence, is now rated as fifth in frequency in types of carcinoma among males,2and proportionately as constituting 10 per cent of all deaths due to cancer.3As recorded in "Vital Statistics of the United States," based on the number per hundred thousand population, the death rate in 1920 was 1.1; in 1930, 2.2; in 1940, 4.0; in 1943, 7.3, and in 1944, 7.9.4The last figure represents 10,537 deaths due to carcinoma of the lungs and pleura. Figures reported in various statistical studies bear a great deal of similarity. It is of paramount importance, in this respect, to note the absolute, as well as the relative, increase in the incidence of this disease.